Package uk.ac.manchester.spinnaker.spalloc

Class SpallocConnection

java.lang.Object

uk.ac.manchester.spinnaker.spalloc.SpallocConnection

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

SpallocClient

public abstract class SpallocConnection
extends Object
implements Closeable

The basic communications layer of the spalloc client. This client assumes that the protocol is line-oriented, but does not assume anything about the formatting of the contents of the lines.

Author:

Donal Fellows

Field Summary

Fields

Modifier and Type	Field	Description
protected final Queue<Notification>	notifications	A queue of unprocessed notifications.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	SpallocConnection(String hostname, int port, Integer timeout)	Define a new connection.

Method Summary

Modifier and Type	Method	Description
protected String	call(Command<?> command, Integer timeout)	Send a command to the server and return the reply.
void	close()	Disconnect from the server.
void	connect()	(Re)connect to the server.
void	connect(Integer timeout)	(Re)connect to the server.
protected abstract String	formatRequest(Command<?> command)	Format a request to be ready to go to the server.
protected abstract Response	parseResponse(String line)	Parse a response line from the server.
protected Response	receiveResponse(Integer timeout)	Receive a line from the server with a response.
protected void	sendCommand(Command<?> command, Integer timeout)	Attempt to send a command as a line to the server.
String	toString()
AutoCloseable	withConnection()	Context adapter.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

notifications

protected final Queue<Notification> notifications

A queue of unprocessed notifications.

Constructor Details

SpallocConnection

@MustBeClosed
protected SpallocConnection(String hostname,
 int port,
 Integer timeout)

Define a new connection. NB: Does not connect to the server until connect() is called.

Parameters:

hostname - The hostname of the server.

port - The port to use.

timeout - The default timeout.

Method Details

withConnection

@MustBeClosed
public AutoCloseable withConnection()
                             throws IOException

Context adapter. Allows this code to be used like this:

 try (var c = client.withConnection()) {
     ...
 }
 

Returns:

the auto-closeable context.

Throws:

IOException - If the connect to the spalloc server fails.

connect

public void connect()
             throws IOException

(Re)connect to the server.

Throws:

IOException - If a connection failure occurs.

connect

public void connect(Integer timeout)
             throws IOException

(Re)connect to the server.

Parameters:

timeout - How long to spend (re)connecting.

Throws:

IOException - If a connection failure occurs.

close

public void close()
           throws IOException

Disconnect from the server.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException - if anything goes wrong

receiveResponse

protected Response receiveResponse(Integer timeout)
                            throws SpallocProtocolTimeoutException,
IOException,
InterruptedException

Receive a line from the server with a response.

Parameters:

timeout - The number of milliseconds to wait before timing out or null if this function should try again forever.

Returns:

The unpacked response from the line received.

Throws:

SpallocProtocolTimeoutException - If a timeout occurs.

SpallocProtocolException - If the socket gets an empty response.

IOException - If the socket is unusable or becomes disconnected.

InterruptedException - If interrupted, eventually

sendCommand

protected void sendCommand(Command<?> command,
 Integer timeout)
                    throws SpallocProtocolTimeoutException,
IOException

Attempt to send a command as a line to the server.

Parameters:

command - The command to serialise.

timeout - The number of milliseconds to wait before timing out or null if this function should try again forever.

Throws:

SpallocProtocolTimeoutException - If a timeout occurs.

IOException - If the socket is unusable or becomes disconnected.

formatRequest

protected abstract String formatRequest(Command<?> command)
                                 throws IOException

Format a request to be ready to go to the server.

Parameters:

command - The request to format for sending. Not null.

Returns:

The text to send to the server. Will have a newline added.

Throws:

IOException - If formatting goes wrong.

parseResponse

protected abstract Response parseResponse(String line)
                                   throws IOException

Parse a response line from the server.

Parameters:

line - The line to parse. Not null. Has the terminating newline removed.

Returns:

The parsed response.

Throws:

IOException - If parsing completely fails.

SpallocProtocolException - If an unexpected valid JSON message is returned (e.g., null).

call

protected String call(Command<?> command,
 Integer timeout)
               throws SpallocServerException,
SpallocProtocolTimeoutException,
SpallocProtocolException,
InterruptedException

Send a command to the server and return the reply.

Parameters:

command - The command to send.

timeout - The number of milliseconds to wait before timing out or null if this function should wait forever.

Returns:

The result string returned by the server.

Throws:

SpallocServerException - If the server sends an error.

SpallocProtocolTimeoutException - If a timeout occurs.

SpallocProtocolException - If the connection is unavailable or is closed.

InterruptedException - If interrupted, eventually

toString

public String toString()

Overrides:

toString in class Object